package com.company.Thread.Concurrent;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.CopyOnWriteArraySet;

public class lockSet {
    public static void main(String[] args) {
        /*
        Set<String> set = new HashSet<>();
        java.util.ConcurrentModificationException
         */
        /*
        解决方案：
        1、Set<String> set = Collections.synchronizedSet(new HashSet<>());
        2、Set<String> set = new CopyOnWriteArraySet<>();
         */
        Set<String> set = new CopyOnWriteArraySet<>();

        for (int i = 0; i < 20; i++) {
            new Thread(()->{
                set.add(UUID.randomUUID().toString().substring(0,5));
                System.out.println(set);
            }, String.valueOf(i)).start();
        }
    }
}
